Nightmares & Disorders
Nightmare disorder in PTSD, and why the dreams do not fade
Ordinary distressing memories lose their charge over successive nights. In post-traumatic stress disorder they do not, and the failure appears to happen during REM sleep itself.
Nightmares are among the most common and most persistent symptoms of post-traumatic stress disorder. Prevalence estimates in PTSD populations commonly exceed 70 per cent, and they are frequently the symptom that persists longest after other symptoms have improved with treatment.
They are also, in the diagnostic criteria, one of the intrusion symptoms — placed alongside flashbacks, which is telling. A post-traumatic nightmare is not simply a bad dream; it is the same intrusive material appearing in a different state of consciousness.
The overnight therapy that fails
The most useful framework comes from the emotion-regulation account of REM sleep.
During REM, noradrenaline — the neurotransmitter of arousal and stress — falls to its lowest concentration of the twenty-four-hour cycle, while limbic and amygdala activity is high. The proposal is that this permits emotionally charged memories to be reactivated and reprocessed without the accompanying stress response, gradually decoupling the memory from its physiological charge.
Studies support the mechanism in healthy participants: amygdala reactivity to emotional images is reduced after a night containing REM, and not after sleep deprivation.
In PTSD this appears to fail. Studies find elevated noradrenergic activity during sleep, disrupted REM continuity, and an absence of the overnight reduction in emotional reactivity. The memory is reactivated repeatedly and never discharged — which produces exactly the clinical picture of a nightmare that recurs unchanged for years.
They frequently replay the event or closely echo it, whereas ordinary nightmares are scenarios. They are highly consistent between occurrences. They can occur in non-REM as well as REM sleep, which is unusual. They provoke strong autonomic arousal. And they drive sleep avoidance — staying up to postpone the risk — which produces sleep deprivation, which increases REM pressure, which worsens the nightmares.
Imagery rehearsal therapy
The best-evidenced treatment, and it does not require processing the trauma itself.
The protocol: select a nightmare, write it down, change it in any way you choose, and rehearse the new version in vivid imagery for ten to twenty minutes daily. Typically four to six sessions.
Barry Krakow's trials in trauma survivors, including sexual assault survivors, showed significant reductions in nightmare frequency and in PTSD symptom severity. The American Academy of Sleep Medicine recommends it as first-line for nightmare disorder.
Clinicians usually begin with a less severe nightmare rather than the most traumatic one, and the rescripting does not need to be logical or heroic — only different.
Prazosin, and the trial that complicated things
Prazosin is an alpha-1 adrenergic receptor antagonist, originally an antihypertensive, and its use here follows directly from the noradrenergic hypothesis: block the receptor, restore the low-noradrenaline conditions REM is supposed to provide.
Multiple small and medium trials, particularly in veterans, showed reductions in nightmare frequency and improvements in sleep quality. It became widely used.
Then a large multi-site trial published in 2018 by Murray Raskind and colleagues — the researcher whose earlier work had established the treatment — found no significant benefit over placebo in a veteran population with chronic PTSD.
The result cooled enthusiasm substantially. Explanations offered include that the trial population had unusually stable, treated PTSD, that blood pressure was lower at baseline in participants, and that dosing may have been insufficient. Others regard it as a straightforward negative result that supersedes the earlier positive ones.
Current guidance is mixed. Several bodies retain it as an option; others have downgraded it. It remains reasonable to try where psychological treatment is unavailable or insufficient, with realistic expectations.
Other approaches
Trauma-focused psychological therapy — prolonged exposure, cognitive processing therapy, EMDR — treats the underlying disorder, and nightmares often improve. Often, but not always; residual nightmares after otherwise successful treatment are common enough that they are frequently targeted separately.
Lucid dreaming therapy has been tested in small trials with encouraging results. Recognising the nightmare as a dream removes much of its power and permits alteration from inside.
Exposure, relaxation and rescripting therapy combines imagery rehearsal with sleep hygiene and relaxation, with good trial support.
Treating comorbid sleep apnoea. Under-recognised and important. Sleep apnoea is common in PTSD populations, it fragments REM, and in some patients nightmare frequency falls substantially with CPAP treatment.
What makes it worse
Alcohol, which suppresses REM and produces rebound in the second half of the night.
Sleep deprivation, through the same rebound mechanism.
Withdrawal from REM-suppressing substances — cannabis in particular, where cessation produces a well-documented surge of vivid and unpleasant dreaming that frequently drives relapse and is rarely warned about.
Benzodiazepines, which are still prescribed for PTSD-related sleep problems despite guidance advising against them, and which suppress REM while adding dependence and, on withdrawal, rebound.
The point worth making to anyone affected
Nightmares in PTSD are treatable, specifically and separately, with a brief psychological intervention that does not require revisiting the trauma in detail.
A great many people assume they are an unavoidable part of the condition and never mention them, and a great many clinicians never ask. That silence is the main obstacle, and it is the easiest one to remove.
